[Improvement][dolphinscheduler-api] delete taskDefinitionServiceImpl useless code

[jackfanwan]

Search before asking

• I had searched in the issues and found no similar feature requirement.

Description

delete taskDefinitionServiceImpl useless code

Are you willing to submit a PR?

• Yes I am willing to submit a PR!

Code of Conduct

• I agree to follow this project's Code of Conduct

[github-actions]

Thank you for your feedback, we have received your issue, Please wait patiently for a reply.

• In order for us to understand your request as soon as possible, please provide detailed information、version or pictures.
• If you haven't received a reply for a long time, you can join our slack and send your question to channel #troubleshooting

[github-actions]

This issue has been automatically marked as stale because it has not had recent activity for 30 days. It will be closed in next 7 days if no further activity occurs.

[github-actions]

This issue has been closed because it has not received response for too long time. You could reopen it if you encountered similar problems in the future.